In the United States, approximately 230,000 women have hysterectomies annually. The primary reason for performing a hysterectomy is the presence of uterine fibroids. These fibroids grow in the wall of the uterus and may range in size up to several inches across. In the United States alone, there are more than six million women with uterine fibroid symptoms who prefer to suffer, rather than endure the risks and inconveniences associated with major surgery, especially a major surgery that results in infertility. Outside of the United States, the situation is much the same, with millions of women suffering with fibroids in need of a safe alternative to hysterectomy.
Recently, another treatment option (uterine artery embolization) has been introduced. Generally, this procedure involves embolization of the arteries which feed the urine fibroid. This results in cutting off the blood supply to the fibroid and the shrinkage of the fibroid over time. However, the unacceptably high rate of complications severely limits its appeal to patients.
Myomectomy, each generally involves the surgical removal of the fibroid through the use of classical surgical procedures, is another treatment option. However, due to its high rate of complications and long recovery time, this option is also not very appealing to patients. Typical complications involve risk of infection, relatively severe postsurgical pain, damage to the uterus and other risks normally associated with such types of surgery. Moreover, such damage may be relatively subtle and may only come to light when the uterus begins to swell in pregnancy and ruptures at a weak point created during the surgery, resulting in loss of the fetus.
Still another alternative to treat the discomfort associated with uterine fibroids is the removal of the endometrium which lines the uterus. However, this procedure results in infertility.
In an attempt to address these issues, an RF ablation probe of the type used to treat tumors in the human liver by hyperthermia has been successfully demonstrated to substantially shrink or eliminate uterine fibroids.
See, for example, U.S. Pat. No. 6,840,935 issued to Lee on Jan. 11, 2005, the disclosure of which is incorporated herein by reference. In that patent a method for treating pelvic tumors, such as uterine leiomyomata, includes inserting an ablation apparatus into a pelvic region and positioning the ablation apparatus either proximate to or into a pelvic tumor. The method further includes using a laparoscope and an imaging device, such as an ultrasound machine, to confirm the location of the pelvic tumor and placement of the ablation apparatus. An ablation apparatus with multiple needles or deployable arms that are inserted into the pelvic tumor is disclosed. The method involves delivering electromagnetic energy or other energy through the ablation apparatus to the pelvic tumor to induce hyperthermia and ablate the tumor.
The particular device disclosed for ablating the tumor in U.S. Pat. No. 6,840,935 is of the type disclosed in U.S. Pat. No. 5,728,143, issued to Gough et al. on Mar. 17, 1998. Generally, that device comprises a plurality of resilient springy RF ablation antennae, or stylets, which are preformed with a curved configuration which they assume after exiting a sharp trocar-tipped catheter. The tip of the catheter is deployed in uterine fibroid tissue to be destroyed. The stylets are then deployed into the tissue to be destroyed.
Generally, as the antennae exit the trocar tip, they pierce the tissue of the uterine fibroid along curved paths which are defined by the preformed springy shape of the stylet. The deployed stylets with their respective preformed shapes and the positions within which they are deployed thus define the ablation volume. Various shape volumes may be defined by varying the configuration of the curves which are preformed into the different springy stylets convey given trocar-pointed catheter. Such devices are manufactured by Rita Medical Systems of Mountain View, Calif. The hallmark of such devices is that the stylets assume their pre-formed configuration as they emerge from the trocar tip.